Airbag devices have become almost standard equipment in recent motor vehicles. An airbag device is a safety device that operates during an emergency such as a vehicle collision, and inflates and deploys an airbag cushion (hereinafter simply referred to as “cushion”) with a gas pressure to receive and protect an occupant. Airbag devices come in various types in accordance with installation locations or applications. For example, in order to protect a driver from impact in the front-back direction (frontal impact), a front airbag device is provided at the center of a steering wheel. In addition, in order to protect the occupant from impacts in the vehicle width direction (side impact) which are caused by a side collision or the like, a curtain airbag device is provided in the vicinity of a ceiling (roof) above a side window, and a side airbag device is provided in a side portion of a seat.
The shape and structure of the airbag cushion are set in consideration of various situations and circumstances. For example, the airbag cushion of the side airbag disclosed in Japanese translation of PCT Application No. PCT/2010-535121 has a double structure including a tube (48) inside an airbag (18). This tube (48) is a part that can be used as a pre-push bag described hereinbelow.
A pre-push bag (also referred to as pre-crash bag) is a mechanism developed to control the impact that can be received by an occupant from the main airbag cushion. The pre-push bag has a bag-shaped structure independent of the overall airbag cushion, and is provided on the inner side of the airbag cushion, the occupant side, and the like. The pre-push bag inflates, deploys and comes into contact with the occupant earlier than the entire airbag cushion. The pre-push bag pushes back the occupant to a certain extent in advance, in order to provide enhanced restraint performance by reducing the force of impact with the entire airbag cushion.
The airbag cushion of the side airbag device is mainly built in the outer side (vehicle outer side) of the seat back in the vehicle width direction, and when an emergency occurs, the airbag cushion ruptures the surface material of the seat back and inflates and deploys in the interior space. An effective method of improving the pre-push function to attain more complete protection of the occupant is to efficiently rupture the surface material of the seat back and cause the pre-push bag to appear in the interior space quickly and smoothly.
In view of such problems, it is an object of the present invention to provide a side airbag device that enables enhanced occupant protection.